1. Field
Embodiments of the present disclosure relate to an oil detection device to detect a level of oil in a compressor, a compressor having the same and a method of controlling the compressor.
2. Description of the Related Art
A compressor has a structure in which a compression assembly to aspirate and compress a refrigerant is disposed in a lower part of a casing and an electric assembly is disposed in an upper part of the compression assembly.
In this case, the compression and electrical assemblies share a rotating shaft, the rotating shaft is rotated based on power generated by the electric assembly and the compression assembly coupled to the rotating shaft is operated through such rotation, thus causing compression.
Supply of oil to the bearings, rolling pistons and the like of the compression assembly is required in order to facilitate rotation of the compression assembly. When oil is disposed in a lower part of the casing, the oil is stored in an oil storage area, pumped by an oil feeder mounted in a lower part of the rotating shaft, and then supplied to the compression assembly.
Oil performs lubrication action and contributes to cooling of the electric assembly. Control of a stable supply of an appropriate amount of oil is essential to the lifespan and operational efficiency of the compressor.
However, as configurations of the compressor gradually become more complicated and compressors are used for large air conditioners, multi-air conditioning systems and the like, pipes in which oil and working fluids flow are increased in length and control of oil levels in the compressors thus gradually become more difficult.
In particular, as the length of pipes increase, an amount of residual oil in pipes increases and amounts of oil stored in the oil storage area are irregularly and greatly changed during operation although an appropriate amount of oil being supplied in an early stage.
For this reason, there is a need for continuously or periodically checking the level of oil in the oil storage area and an oil collection operation to collect oil in the compressor may be required when a level of oil is determined to be an appropriate level or less, as a result of the check.
Such an oil level is commonly checked by the naked eye through a transparent window formed in the compressor casing, but this method is not economically efficient and an oil collection operation is thus actually performed on a cycle of a predetermined time, regardless of oil levels.
However, in this case, in actuality, the oil collection operation may be compulsively performed although an oil level is sufficient. For this reason, for example, air conditioners inefficiently consume energy while not providing cooling.
In recent years, an oil collection operation has been developed that may be performed based on oil level detected through an additional oil level sensor mounted in the compressor casing.
The oil level sensor as described above may have the effects of reducing unnecessary oil collection operation, thus decreasing energy consumption and increasing compressor operation time according to intended application. However, a calculation operation for converting a physical property value into an oil level is involved, thus disadvantageously making an overall configuration complicated and increasing cost, because a physical property value changed according to contact with oil is read, an oil level corresponding to the measured physical property value is calculated and an actual oil level is checked, the actual oil level is compared with a preset level and whether or not oil collection operation is performed is determined.